Medical devices are used for a number of purposes, including the reinforcement of recently re-enlarged lumens, the replacement of ruptured vessels, and the treatment of disease such as vascular disease by local pharmacotherapy, i.e., delivering therapeutic drug doses to target tissues while minimizing systemic side effects. Such localized delivery of therapeutic agents has been achieved using medical implants, such as stents, which both support a lumen within a patient's body and place appropriate coatings containing absorbable therapeutic agents at the implant location. Examples of such medical devices that can be used for localized delivery of therapeutic agents include catheters, guide wires, balloons, valves, shunts, filters (e.g., vena cava filters), stents, stent grafts, vascular grafts, intraluminal paving systems, implants and other devices used in connection with drug-loaded polymer coatings. Such medical devices are implanted or otherwise utilized in body lumina and organs such as the coronary vasculature, peripheral vasculature, esophagus, trachea, colon, biliary tract, urinary tract, prostate, brain, and the like.
The process of applying a coating onto a medical device, such as a stent, may be accomplished by a number of methods including, for example, spray coating, spin-coating, dip coating, meniscus coating, gravure coating, ink jet printing, and electrostatic deposition. For certain applications only a specific portion, such as the outer or inner surface, of a medical device requires coating. For other applications, different portions of the medical device require coatings of different thicknesses. Given the often complex geometry of the medical device and the fluid nature of the coating it is difficult to tightly control the specific areas on the medical device that receive coating and the thicknesses of the coating. Therefore, there is a need for an improved method and device for coating medical devices that allows for greater control of the location and/or thickness of a coating application.